Engine and gearbox swap from four speed to six or eight speed on 2008 Z71 ?

[Robert T]

I have a 2008 Tahoe Z71 in need of a new engine ! 338thousand kilometers from new and could rebuild, just wonder if anyone has done an engine and gearbox swap for a newer motor with either the six speed or 8 speed box, or possibly a Denali swap with an eight speed box, just wondering which one one be the eisiest swop ( 6 speed i've been told) or how much work to go with a newer denali or eight speed ? is there a conversion kit ? i'd be greatful for any info ? thanks

 

[Joseph Garcia]

I recently researched a potential high performance option for me that kind of parallels your question. I wanted to put an LT4 and its matching 10 speed high performance transmission in my 07 Yukon XL Denali, and I spoke with knowledgeable folks at GM Performance, GM crate engines, Summit Racing, and Summit's engine builder. They all told me that there are too many core and electrical interface differences between the LT4/10 speed trans combo generation and my 07 electrical and CANBus system generation to make the conversion a reality. If I just wanted to race my Denali (which I do not) and did not care about any loss of functionality in the interior of the truck, the swap 'could' be possible, but still not easy. All of their recommendations to me was to find a knowledgeable LS engine builder and have them totally rebuild my existing L92 engine with the appropriate high performance internal parts and put a supercharger on it.

 

[Miami-Dade]

@Robert T Moved you here from 2021+section.
Welcome from Miami&NYC!

 

[Marky Dissod]

I have a 2008 Tahoe Z71 in need of a new engine. 338,000km from new and could rebuild.
just wonder, if anyone has done an engine and gearbox swap for a newer motor with either the 6L80 or 8L90E, or possibly a Denali swap with an 8L90?
just wondering which one one be the easiest swap (6L80E I've been told),
or how much work to go with a newer denali or 8L90E? is there a conversion kit?

To paraphrase Joseph Garcia:
6L80E MIGHT BE POSSIBLE. MAYBE.
8L90E or 10L90E, you'd be in uncharted waters.

'kilometers' instead of 'miles' ...
does your local gov't let you upgrade to a 6.0L engine from 2008-2014?
That would be MUCH easier and cheaper than trying to use a newer engine.
Again, you'd be in uncharted waters.

 

[petethepug]

I’ve seen one YouTube clip of an 8SP 8L90 going into an 07-14 Gen truck but didn’t save a link. I’ll post it up when I find it again.

So yes, you can also go 6.2 w/ a 6SP 6L80 as that architecture is already in our Gen truck as well as the uncommon 08/09 Tahoe w/ the 6.2L.

The second option is the way I’d go as it would essentially be a part swap from a known (totaled) 6.2 w/ a 6SP trans like a Denali. That would also give you the option to plunk in it’s AWD to deal with rain & snow.

Sorry to hear about its demise but congrats on the journey.

So don’t forget 07/08 6.2L Denali is L92 385hp No AFM, 09 Denali is 403hp L9H e85 No AFM and 10-14 is L94 403 hp e85 with AFM.

Oh yea, then there’s L96 drop in, iron block/alum head L96 6.0 Reg fuel 365 hp No AFM from the 3/4 & 1 ton gasser trucks. Later models also run e85.

Subscribed!

 

[petethepug]

I’ll paste this here

8L90 to 10L80 Swap

I have a 2015 GMC Yukon Denali 4WD with the 8L90 tranny. I'm swapping in a 10L80 and would like to know whether or not my current TCM will support it or if I will need to get a different TCM. This is being matched up to a built LT-1 from a C7 w/ LT-2 Intake. Any input is greatly appreciated.

forum.hptuners.com

 

[Foggy]

Just my 2 cents... the 8 speed is a POS... some of it due to design, some
due to programming etc...
Too many problems to waste your time and money on

 

[Charlie207]

Just my 2 cents... the 8 speed is a POS... some of it due to design, some
due to programming etc...
Too many problems to waste your time and money on

They crammed 8 forward ratios into the same size case as the 6L80.

 

[Robert T]

I recently researched a potential high performance option for me that kind of parallels your question. I wanted to put an LT4 and its matching 10 speed high performance transmission in my 07 Yukon XL Denali, and I spoke with knowledgeable folks at GM Performance, GM crate engines, Summit Racing, and Summit's engine builder. They all told me that there are too many core and electrical interface differences between the LT4/10 speed trans combo generation and my 07 electrical and CANBus system generation to make the conversion a reality. If I just wanted to race my Denali (which I do not) and did not care about any loss of functionality in the interior of the truck, the swap 'could' be possible, but still not easy. All of their recommendations to me was to find a knowledgeable LS engine builder and have them totally rebuild my existing L92 engine with the appropriate high performance internal parts and put a supercharger on it.

Thanks for sharing this information

 

[petethepug]

Oh well, high hopes. At least I don’t feel bad about potentially missing the boat on a 10SP swap since I just replaced the 6SP.